TITLE: GCN CIRCULAR NUMBER: 42592 SUBJECT: GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/11/05 18:13:59 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo@astro.unam.mx> Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), Camila Angulo (UNAM), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of the SVOM GRB 251104A (Bernardini et al., GCN Circ. 42581) using the DDRAGO wide-field, two-channel imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-05 05:32:28 to 06:59:02 UTC (from 12.02 to 13.46 hours after the trigger) and obtained 64 minutes of exposure in the r and z filters. At the time of the observation the GRB was about 6 degrees from the full Moon. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the ECLAIRs source position (Bernardini et al., GCN Circ. 42581) down to the following 5-sigma limit: r > 21.3 z > 20.8 We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42592. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...